Commercial airbeds have been growing steadily in popularity. Many types of airbeds have been developed for a variety of applications over the years, ranging from simple and inexpensive airbeds that are convenient for temporary use (such as for house guests and on camping trips), home-use airbeds that replace conventional mattresses in the home, to highly sophisticated medical airbeds with special applications (such as preventing bedsores for immobile patients). With respect to home-use and medical airbeds, more and more consumers are turning to these types of airbeds for the flexibility in firmness that they offer, allowing consumers to adjust their mattresses to best suit their preferences.
Conventional home-use and medical airbeds generally include at least a few main components: a mattress with at least one chamber that can be filed with air, a unit for pumping air into the chamber, and appropriate connections between the mattress and the pumping apparatus. The pumping unit may further include a pump connected to a manifold, with a control mechanism and valves for controlling the pumping of air into the mattress and releasing the air out of the mattress. Conventional pumps used in airbeds are “squirrel-cage” blowers and diaphragm pumps.
The squirrel-cage blowers used in airbeds are relatively inexpensive and simple pumps that rely on a fan to push air into the mattress. While the squirrel-cage blower is able to achieve a relatively high flow rate (e.g. around 75 L/min) and inflate a mattress relatively quickly, it is unable to produce pressures that are high enough to meet the desirable range of pressure for all home-use and medical airbeds (up to about 1 psi), as squirrel-cage blowers are generally limited to about 0.1-0.5 psi. Squirrel-cage blowers tend to be inefficient and therefore will generate higher levels of heat when they are running compared to diaphragm pumps.
The diaphragm pumps used in airbeds, which rely on quasi-positive displacement technology, are generally able to achieve pressures of up to about 5 psi, well beyond the requirements of the airbed industry. However, diaphragm pumps are not capable of as much air flow as squirrel-cage blowers (limited to about 25-50 L/min), and thus take a longer amount of time to fill an air mattress. Diaphragm pumps also generate a moderate amount of noise, but less than squirrel-cage blowers. Diaphragm pumps, for the same relative performance as a squirrel-cage blower, will be two to three times more expensive.
More sophisticated airbeds used in medical applications (e.g. home-care airbeds) have been able to deal with these problems to some degree by integrating both a diaphragm pump and a squirrel cage blower in their airbeds, as well as adding a noise-cancelling housing to encase the pumps. These medical airbeds can start off by filling the airbed quickly at a low pressure with a squirrel cage blower, and switch over to a diaphragm pump to finish the filling and achieve the desired pressure. Additionally, medical airbeds may take into account whether the patient on the bed is asleep or awake in determining which pump to use (e.g. using the noisier squirrel cage pump for rolling over a patient that is awake, or using the relatively quieter diaphragm pump for supplying a constant flow for a wound-care type mattress running while the patient is asleep). However, these solutions result in a steep increase in cost, as well as increasing the size and complexity of the entire pumping unit.
It will be appreciated that the foregoing is a discussion of problems discovered and/or appreciated by the inventors, and is not an attempt to review or catalog the prior art.